Density-weighted mean wind

From Glossary of Meteorology

density-weighted mean wind

The wind vector representing an average speed and direction over an atmospheric layer of finite depth, accounting for changes in air density over the depth of the layer. The contribution of density generally makes this a superior estimate to a standard mean wind estimate, since winds at heights with higher density (i.e., nearer to the surface) will contribute more to the average value than those at heights with lower density (i.e., at higher altitudes); per unit volume, more air molecules at lower altitudes contribute to the mean wind than those at higher altitudes.

Density-weighted mean wind is commonly used as an estimate of the steering current of a thunderstorm contained within the vertical layer.

Mathematically, the density-weighted mean u and υ wind components are calculated according to Houston (2017):

Density-weighted mean wind.gif

where ρ(z) is the density at height z, h and H are the lower and upper heights, respectively, of the layer over which the average is being computed, and u(z) and υ(z), are the values of the u and υ wind components at height z.

Houston, A.L., 2017: The possible role of density current dynamics in the generation of low-level vertical vorticity in supercells. J. Atmos. Sci., 74, 3191–3208,

Term edited 3 December 2021.

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